With luck, you might be able to clean an EGR once but the second time it falls to bits. And the cost of fixing an EGR depends on the dismantling. On some engines it's not too difficult but on some Volkswagens it's a long and tedious job. DPFs are now "checked for tampering" in the UK MoT, so any undocumented sign of removal and replacement can mean a fail.

Two different substances can need to be cleaned from DPFs. The easy one is soot, sometimes cleared by an additive or a forced regeneration. The more difficult one is ash that can fill up and block a DPF by 80,000 miles. That needs to be chemically cleaned, which usually means sending the DPF away to someone like Ceramex who clean the ash out and return the DPF tested and documented for the MoT.